Planar Lenses

The latest edition of Camera Lens News, from Carl Zeiss, has just been published and includes a feature on Planar lenses. Given that the Planar design was developed by Paul Rudolf for Carl Zeiss, CLN is the ideal source of information on this topic. Here is a summary of some of the points covered.

This ‘blog is based on a Carl Zeiss article that is available online at the link given below. Supplementary information has also been provided where appropriate for readers who simply want to know a little more about the iconic Planar design. Readers who want the full Planar story are advised to consult the very detailed paper that is referenced in Issue 40 of Camera Lens News: the full article can be found online at http://blogs.zeiss.com/photo/en/wp-content/uploads/2011/07/en_CLB_40_Nasse_Lens_Names_Planar.pdf

The important feature about the Planar design, as its name suggests, is the flat (planar) image field that it projects. The significance of this is not obvious until it is realised that lenses tend to project curved image fields, which means that the sensor also has to be curved if image sharpness is to be maintained right across the picture. Curved sensors, whether those sensors are film or solid-state, are not very practical whereas a perfectly flat sensor is achievable. For this reason, lens designers try to create flat image fields – and that is where the Planar design is so strong.

Planar lenses are symmetrical, which means there is the same arrangement of elements to each side of the centre of the lens (where the aperture is located). As was the case for so much in early optics, the basic arrangement used was devised for use in telescopes (before photography was invented). Rudolf’s contribution was to realise that the symmetrical arrangement could be modified to incorporate paired elements that had the same refractive index (light-bending power) but different dispersion characteristics (separating of different colours).

This meant that Rudolf’s Planar offered superior colour correction, which in turn made it well suited for use in process lenses (used for copying applications). As is often pointed out in What Digital Camera’s lens tests, high-contrast test targets tend to reveal chromatic aberration much more strongly than many real-world images – and this is no different to any other copying situation that involves stark black-and-white patterns or text.

Inevitably, there were problems with the Planar design: in particular, the multiple surfaces and strong curvature of the elements caused ghosting from internal reflections and also meant a significant level of light loss due to these same reflections. Ironically, later designs increased the number of elements but the development of newer, high refractive-index, glasses allowed the curvature to be decreased.

This adaptability, coupled with the option to provide a wide maximum aperture, explains the longevity of the Planar (and its various, sometimes non-symmetrical derivatives). Dr Hubert Nasse’s historical and technical overview (linked above) highlights Stanley Kubrick’s use of a 50mm f/0.7 Planar lens in the film Barry Lyndon in order to record scenes lit by candlelight!

Sadly, that record-breaking lens could only just cover an APS-C sensor (not full-frame) and weighed nearly 2kg. It was also very expensive: one went to auction last year and sold for 90,000 Euros! Furthermore, the distance between the back of the lens and the sensor (film) was just 5.3mm – meaning that there would be no room for any mirror box, so use on a reflex camera body would be totally out of the question.

There is much more information in Dr Nasse’s paper so if this brief summary has whetted your appetite please read the full version – and register to receive notice of future editions of Camera Lens News at http://blogs.zeiss.com/photo/en/?page_id=2.

slim pills

With the 1st 3 times you just take 1 capsule each morning (15-30 min prior to breakfast). I did see a tiny bit of nauseau on day two right after using it however it subsided promptly. You will be also supposed to drink 91 oz of fluid a day (which is sweet, it’s making me consume additional water). I must confess I was shocked by exactly how much it suppressed my appetite. Instead of having all working day, or thinking of food stuff all the time, I didn’t!!! It allowed me to make healthier choices because I wasn’t craving junk. In any case, the initial working day I misplaced two lbs and was giddy with excitement. I basically called my hubby into the bathroom to watch me get on the scale, that is how stoked I had been. The next working day I ate alot far more than I had wanted way too (my goal is 1400 calories a working day). Ok, enable me just be actual honest right here, I probably ate 2500 calories that day (McDonalds for dinner and had a donut – I understand I know). And yet I did NOT acquire any bodyweight back again. I used to be actually expecting to have attained back what I had missing and was fearful I had sabotaged myself. I did not lose but I did not achieve either – SWEET. Day three I also ate a little more than I wanted (not positive the calories) but all over again I did not get. I still advise that you try to make healthier choices and work out to maximize your pounds decline nevertheless. I lost another lb yesterday (ate around 1400 calories but didn’t get the job done out). So 3 lbs shed in 4 days and two of these times I did not work out and two of those people times I ate extra than I originally intended. I am stoked!! Just imagine if I had labored out and eaten wholesome all 4 times, I probably would be down even extra!! I’d personally definitely suggest this item to individuals who need to have assist with suppressing their appetite so they can shed body weight. I can not hold out to see how this continues. slim pills http://officialsuperslim7r.blogbaker.com/

Ashok

Very interesting

Camera selector tool

Competition

Create stunning slideshows from your images with this great software program. MAGIX Photostory 2015 Deluxe offers over 300 effects, animations and decorative elements. You can combine images to make panoramas…